Mercenaries were common until the 18th century. During the Renaissance, many Italian city-states had no standing armies and relied entirely on mercenary forces. The British used them during the American Revolution, and everyone used Swiss mercenaries at one point or another.[1] (When Stalin asked how many divisions the Pope had, the Generalissimo was thinking of the Pontifical Swiss Guard in its pretty uniforms.[2]) However, even then many thinkers foresaw the dangers in using mercenaries. Machiavelli wrote that a mercenary, having no allegiance, will eventually hold the prince who employs him hostage for increasing amounts of money.[3]

The widely held image of the notoriously undisciplined, cowardly mercenaries who will switch sides at the drop of a hat and roam the land looting, raping, and murdering, however, is (mostly) wrong: this is largely an artifact of the middle ages, when mercenaries could be rewarded with land and noble title for their deeds, something the existing nobility was not at all fond of. Therefore, any and all instances of mercenary disloyalty were played up. While it is often said that mercenaries only fight for money, it is generally forgotten that in this period most regular soldiers had to fight out of feudal obligation rather than any form of patriotism.

Most (although of course not all) examples of mercenaries deserting their employer or terrorizing the population were and are results of them either not being paid or being allowed or maybe even encouraged to do so by their employer. Wallenstein's historical concept of "war that feeds the war" would be one example; Academi, née Blackwater, in Iraq might be considered a second one.

After the rise in the popularity of nationalism in Europe, the use of mercenaries declined sharply, such that none were used in the great wars of the 19th century or in the world wars of the 20th[citation needed] - apart from cases like the Gurkhas[4]
and the French Foreign Legion[5] and the foreign volunteers in the Wehrmacht. Mercenaries thrived in Africa up into the 20th century. Recently, some people have accused the United States of using mercenaries, such as the "defense contractors" of Blackwater and others. People may frown on open mercenaries, but bribingsubsidizing allies to join in your Coalition of the Willingmilitary adventures counts as OK. And supporting friendly countries to fight your proxy wars for you looks like a Good Thing, because that means fewer of Our Boys come home in body-bags. If the friendly countries use your transferred resources to invest in skilled or keen mercenaries, that's None of Our Business.